The use of chiral auxiliaries is a valuable tool in the synthesis of complex natural products. Usually natural products occur as optically active molecules, and conventional organic synthesis generally produces the racemic mixture, comprised of non-optically active forms, which require complex resolution into their optically active components. The use of chiral auxiliaries in a synthetic procedure have the big advantage of producing one or the other optically active form directly without resorting to complex resolution techniques.
Different classes of chiral auxiliaries are known in the art for the stereoselective synthesis of many natural products, including naturally occurring amino acids. See for example, Evan's oxazolidinones.sup.1, Oppolzer's sultams.sup.2, Meyer's oxazolines.sup.3 and others.sup.4, which have been developed for asymmetric synthesis of biological molecules. (See in back for reference cites.) Further, Masamune and coworkers have reported benzopyranoisoxazolidines.sup.6 and bicyclicisoxazolidines as chiral auxiliaries.sup.7.
What is constantly being searched for in the art is a new class of chiral auxiliaries which offer greater ease and versatility in their application for producing optically active natural products.